Final Report: Developing Liquid Protection Schemes for Fusion Energy Reactor First Walls

Over the last year, the Georgia Tech group has experimentally studied vertical turbulent sheets of water issuing downwards into atmospheric pressure air at Reynolds numbers Re = U{sub 0}{delta}/{nu} = 53,000 and 120,000 and Weber numbers We = {rho}U{sub o} {sup 2}{delta}/{sigma} = 2,900 and 18,000, respectively. Here, U{sub o} is the average jet speed, {delta} is the jet thickness (short dimension) at the nozzle exit ({delta} = 1 cm), and {nu}, {rho} and {sigma} are the kinematic viscosity and density of water and the surface tension at the air-water interface, respectively. These Re and We values are about 50% and 20% of the prototypical values for HYLIFE-II, respectively. In this report, the flow coordinate system is defined so that the origin is at the center of the nozzle exit, with the x-axis along the flow direction, the y-axis along the long dimension of the nozzle, and the z-axis along the short dimension of the nozzle (cf. Fig. 1). During the final year of this project, we have made three contributions in the area of thermal-hydraulics of thick liquid protection, namely: (1) Experimentally demonstrated that removing as little as 1% of the total mass flux using boundary-layer (BL) cutting can reduce the number density of the drops due to turbulent breakup of the liquid sheet below the maximum background density levels recommended for HYLIFE-II of 5 x 10{sup -19} m{sup 3}; (2) Shown that a well-designed flow conditioning section upstream of the nozzle can greatly reduce surface ripple, and that boundary-layer cutting can be used in conjunction with well-designed flow conditioning to further reduce surface ripple below the 0.07{delta} beam-to-jet standoff proposed for HYLIFE-II; and (3) Quantified how different flow conditioner designs affect the rms fluctuations of the streamwise (x) and transverse (z) velocity components in the nozzle itself (i.e., upstream of the nozzle exit) and affect surface ripple in the near-field of the flow, or x {le} 25{delta}. The rest of this section details these conclusions. In all cases, further details of this work can be found in the doctoral dissertation by Durbin

Effects of polymeric additives on the likelihood and/or severity of vapor explosions

Issued as Report, Project E-25-645Report has author: Michael F. DowlingReport has title: Effects of polymeric additives on the likelihood and/or severity of vapor explosions

Experimental Investigation of the Root Cause Mechanism and Effectiveness of Mitigating Actions for Axial Offset Anomaly in Pressurized Water Reactors

Axial offset anomaly (AOA) in pressurized water reactors refers to the presence of a significantly larger measured negative axial offset deviation than predicted by core design calculations. The neutron flux depression in the upper half of high-power rods experiencing significant subcooled boiling is believed to be caused by the concentration of boron species within the crud layer formed on the cladding surface. Recent investigations of the root-cause mechanism for AOA [1,2] suggest that boron build-up on the fuel is caused by precipitation of lithium metaborate (LiBO2) within the crud in regions of subcooled boiling. Indirect evidence in support of this hypothesis was inferred from operating experience at Callaway, where lithium return and hide-out were, respectively, observed following power reductions and power increases when AOA was present. However, direct evidence of lithium metaborate precipitation within the crud has, heretofore, not been shown because of its retrograde solubility. To this end, this investigation has been undertaken in order to directly verify or refute the proposed root-cause mechanism of AOA, and examine the effectiveness of possible mitigating actions to limit its impact in high power PWR cores

Experimental facility for spray visualization and performance assessment

Issued as final repor

Thermal performance of helium-cooled divertors for magnetic fusion applications

Issued as final reportForschunszentrum Karlsruhe GMB

Manned spacecraft external thermal control using the Johnson tube heat pump

Issued as Final report, Project E-25-W41Final report has author: L.G. Johnso

Investigation of 100 CM2 test hardware hydraulic characteristics Via theoretical, experimental, and numerical tools

Issued as Monthly budget reports [nos. 1-9], Task report, Quarterly progress reports [nos. 1-2], Draft outling, and Final report, Project E-25-A04Final report has author: Dennis L. Sadowski

University Reactor Matching Grants Program

During the 2002 Fiscal year, funds from the DOE matching grant program, along with matching funds from the industrial sponsors, have been used to support research in the area of thermal-hydraulics. Both experimental and numerical research projects have been performed. Experimental research focused on two areas: (1) Identification of the root cause mechanism for axial offset anomaly in pressurized water reactors under prototypical reactor conditions, and (2) Fluid dynamic aspects of thin liquid film protection schemes for inertial fusion reactor chambers. Numerical research focused on two areas: (1) Multi-fluid modeling of both two-phase and two-component flows for steam conditioning and mist cooling applications, and (2) Modeling of bounded Rayleigh-Taylor instability with interfacial mass transfer and fluid injection through a porous wall simulating the ''wetted wall'' protection scheme in inertial fusion reactor chambers. Details of activities in these areas are given

Goddard Expansion and Kinetic-Theory for Solutions of Rodlike Macromolecules

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Bayesian Parameter Estimation of the <i>k</i>-ω Shear Stress Transport Model for Accurate Simulations of Impinging-Jet Heat Transfer

Given the lack of fusion-relevant component test facilities, current estimates of the thermo-fluid performance of plasma-facing components are based for the most part on numerical simulations. A major source of uncertainty in these simulations is the semiempirical turbulence (closure) models for the Reynolds stresses appearing in the governing Reynolds-averaged Navier-Stokes equations, which involve a set of constants that depend upon the flow. The objective of this study is to evaluate Bayesian parameter estimation of turbulence closure constants in ANSYS Fluent to model heat transfer in impinging jets. The Bayesian statistical calibration produces a probability distribution for these constants from experimental data; the maximum a posteriori estimates are then taken to be the calibrated constants, or parameters. The turbulence model constants are calibrated using an experimental study of a submerged jet of air impinging on a flat heated surface at Reynolds numbers Re = O(104) and impingement distance in jet diameters H/d = 2. Numerical predictions using the calibrated model parameters are then compared with those generated using the default constants. Predictions obtained with model parameters calibrated on datasets of two different sizes are compared to evaluate the effect of the number of calibration samples. Finally, the extrapolative ability of the calibrated model is examined by predictions at a Re beyond the calibration values.</p